Spinal muscular atrophy: What is it?

Baby Avery Lynn Canahuati, whose parents created a bucket list for her after she was diagnosed with spinal muscular atrophy, died at just 5 months on Monday.

Mike and Laura Canahuati, who live in Texas, created a bucket list blog for their daughter, who was expected to die by the age of two because of her genetic disorder. Their blog quickly went viral, amassing over 1 million page views and spreading the word about spinal muscular atrophy, or SMA, ABC News reported.

According to FightSMA, spinal muscular atrophy kills more babies than any other genetic disease.

It's a group of diseases that affect the motor neurons of the spinal cord and brain stem. SMA is genetic; a person must usually get the defective gene from both parents to be affected.

About 4 out of every 100,000 people have the condition.

Type I, the disease that Baby Avery was diagnosed with, is the most severe form, and is also called Werdnig-Hoffman disease. According to the National Institute of Health, babies born with SMA type I are born with very little muscle tone, weak muscles and feeding and breathing problems.

Other symptoms include:

Breathing difficulty, leading to a lack of oxygen

Feeding difficulty (food may go into the windpipe instead of the stomach)

Floppy infant (poor muscle tone)

Lack of head control

Little movement

Weakness that gets worse

People with SMA type I rarely live longer than two or three years because of respiratory problems and infections.

According to CBS News, Avery seemed perfectly healthy when she was born, however her mother noticed that she wasn't progressing normally. When she was diagnosed with SMA, her parents made her a bucket list, which quickly went viral. 

Her bucket list can be viewed here.